Note: Note that the errors on the
proper motions are large (∼50mas/yr), and therefore the positions
computed at an epoch different from 1991.25 have a large (∼0.4")
uncertainty.The Tycho Epoch Photometry data can
be accessed from the morePhoto column
(includes VT, BT and Hp photometric data for Hipparcos stars
[filter responses]

Note: USNO-A2.0
contains 526,280,881 sources, and is based on a
re-reduction of the Precision Measuring Machine (PMM) scans
from POSS-I O and E plates (>=-18°) and SRC-J and
ESO-R plates (<=-20°).
USNO-A2.0 was created by Dave Monet ()
and collaborators at
Flagstaff Station, U.S. Naval Observatory.
The major difference between USNO-A2.0 and its previous version
USNO-A1.0 is that A1.0 used the
Guide Star Catalog as its reference frame whereas
A2.0 uses the ICRF as realized by the
USNO ACT catalog (Urban et al. 1997).
The VizieR search engine uses an
on-line compressed version
(3.6Gbytes) which was generated at CDS.

Note: The Guide Star Catalog has been constructed to support the
operational need of the Hubble Space Telescope.
It contains over 25 million positions for about 19 million
objects, of which more than 15 million are classified as stars.
The version 1.2 is a new astrometric reduction which results in
absolute position errors about 0.3-0.4 arcsec.
(see GSC pages at URL http://www-gsss.stsci.edu/gsc/gsc.html)

Note: The construction of the
GSC-II
is still in progress: this
version has no proper motions, and the magnitude limits are 18.5 in F (red)
and 19.5 in J (blue). The data are copyrighted, check
the data use Policy.

Note:
The USNO-B Catalog presents positions, proper motions,
magnitudes un blue, red and infrared, as well as star/galaxy estimators
for 1,045,175,762 objects derived from 3,648,832,040 separate observations.
The data were taken from scans of 7,435 Schmidt plates
taken from various sky surveys during the last 50 years.
USNO-B1.0 catalog was created by Dave Monet and collaborators
at http://www.nofs.navy.mil/data/fchpix/ Note that the star/galaxy estimators may be mixed up
in dense regions.

Stellar parameters for the stars in the Hipparcos catalog within 100pc from the Sun included in the ranges for the radius, mass, effective temperature and gravity described in Section 4 of the paper. (17219 rows)